A Two-Layer Stacked Polycrystalline Silicon Thin Film Transistor Complementary Metal Oxide Semiconductor Inverters Using Laser Crystallized Channel with High-k and Metal Gate on Si

Abstract

The fabrication methods and characteristics of polycrystalline silicon (poly-Si) thin film transistor (TFT) stacked complementary metal oxide semiconductor (CMOS) inverters were demonstrated the feasibility for high performance logic circuit applications was verified. The laser crystallization processes were compatible with the poly-Si TFT stacked CMOS inverters and the laser crystallized poly-Si films showed uniform grain size with low surface roughness and excellent crystallinity. In order to fabricate three-dimensional (3-D) stacked poly-Si CMOS inverters, the p-channel MOSTFTs (PMOS) at upper poly-Si layer were stacked on the n-channel MOSTFT (NMOS) at lower poly-Si and interlayer dielectric (ILD) layer. The HfO2 gate dielectrics and Pt metal gates were applied to the upper PMOSTFT to avoid the degradation of lower NMOSTFT. The CMOS inverters fabricated by stacking the poly-Si TFTs revealed good characteristics for the 3-D integrated CMOS applications.